Although some sectors of dentistry have benefited from technological advances, dental caries is still a major problem. Prevention and treatment of dental caries by fluorine is considered a major advance in public health. Nevertheless fluorosis, caused by ingestion of excessive amounts of fluorine during the period of teeth formation, is of great concern. In accordance with the homeopathic doctrine, minimum doses of fluorine and other substances could prevent and/or treat caries. In this experiment, we compared the preventive action of fluorine and evaluated the effect of homeopathic medicines on the teeth of rats fed a cariogenic diet. None of the groups included in this study developed caries. However, microscopy revealed the presence of precipitate and/or deposit in the groups treated with homeopathic medicines. This phenomenon might be due to deposit in the dental surface or precipitation of bacterial plaque or calcium salts. It was not possible to identify the composition of the deposit/precipitate due for technical reasons. In one of the groups treated with homeopathic medicines fur loss was observed in 40% of animals. These reactions might be caused due to the action of the homeopathic medicines.